Answers ? ! i dont know how to solve these

Write the point-slope form of the line passing through (2, -12) and parallel to y=3x.

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )